Vehicles such as agricultural and/or lawn and garden tractors are commonly provided with a power takeoff shaft that is used to drive attachments such as snow blowers, power brooms and drawn implements which require a powered drive input.
Typically the PTO shafts are provided with a clutch that is operated by the hydraulic system of the tractor. When the PTO shaft is not being used to drive an attachment or implement, the clutch is disengaged and the shaft is not powered. When the clutch is disengaged, the vehicle hydraulic system continues to operate and hydraulic fluid flows through the system, producing small residual torques on the drive components for the PTO shaft. Consequently, even though the torques are small, the PTO shaft may continue to slowly turn when the clutch has been disengaged. When an operator wants to connect an attachment or implement to the PTO shaft, such inadvertent rotation of the PTO shaft could prove troublesome.
Accordingly, spring steel snubber brakes have been provided to prevent inadvertent rotation of the PTO shaft when the clutch is disengaged. Present snubber brakes utilize a pair of U-shaped flat springs that are clamped around approximately three-fourths of the PTO shaft. These flat springs are in constant sliding contact with the shaft to retard its rotation, particularly when the power to the PTO shaft has been stopped. While these snubber springs serve to prevent inadvertent rotation of the PTO shaft when it is declutched, they create a friction on the shaft since they bear on the PTO shaft at all times, even when it is operating at normal speeds to drive attachments and/or implements. Accordingly, they cause a parasitic friction loss that robs the PTO system of horsepower, particularly at higher speeds.
Therefore, it would be desirable to provide a PTO shaft brake which functions to prevent inadvertent rotation of the shaft when the PTO clutch has been disengaged, as well as one which does not reduce the horsepower of the PTO system when it is rotating at operating speeds.